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EM waves and forces

  1. Feb 16, 2014 #1
    Would a particle kept in the path of an electromagnetic wave experience a force?
    Both magnetic and electric field are present, so the equation of motion may be complex, but i have never seen my textbook refer to the the possibility of an em wave causing a charged particle to move.
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  3. Feb 16, 2014 #2

    Vanadium 50

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    EM waves cause particles to move all the time. That's how a radio antenna works - the radio wave causes the electrons in the antenna to move, which produces a current, which is detected by the radio receiver.
  4. Feb 16, 2014 #3
    So if a charged particle is kept in a ray of light, would it begin to accelerate?
  5. Feb 16, 2014 #4

    Vanadium 50

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    I'm not sure what you mean by "kept in a ray of light", but yes, the EM field of light can accelerate charges.
  6. Feb 16, 2014 #5
    Well of course a light wave can accelerate a charged particle, an EM wave has the M part in it, which would affect a charged particle.

    What I've always wondered is, if you had, say, an atom of silicon floating in space and a stream of photons came flying at it, a few photons would hit the silicon atom. Would these collisions cause the silicon atom to move?

    I know a photon is massless, so conservation of momentum says no, but it also has a lot of energy attached to it (doesn't it?) so from E=mc^2, shouldn't it be able to impart some force?
  7. Feb 16, 2014 #6
    The photon has momentum even though it's massless. So there is no contradiction. Conservation of momentum does not say "no".:smile:

    But I think you should start a new topic, as you bring a different question.
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